Here’s why using a cell phone while driving can be dangerous

Talking on the phone or even talking to a passenger while driving can be dangerous, a new study has found.
The simple fact is that one should just not talk on the phone when driving. (Shutterstock)

Being on the phone behind the wheel is often blamed for road deaths, but is keeping connected in a car always dangerous?New research from the University of Iowa is helping us understand how even a simple conversation can affect your brain’s ability to focus on the roadway. Researchers used computerized experiments that tracked eye movements while asking subjects to answer true or false questions. Respondents who answered the questions took about twice as long to direct their eyes to a new object on the screen than those not required to respond or who were asked no questions at all.The experiments mimic a scenario in which a driver is using a cell phone or having a conversation with a passenger, said researcher Shaun Vecera. It’s the first study known to examine attentional disengagement as the possible cause of poor driving while using a cell phone.“What this study suggests is the reason you should be cautious (when talking on the phone while driving) is it slows your attention down, and we’re just not aware of it because it happens so fast,” Vecera added. The delay is about 40 milliseconds, or four-hundredths of a second, which may not seem like a long time. But that delay compounds: Every time the brain is distracted, the time to disengage from one action and initiate another action gets longer.

“It’s a snowball effect,” Vecera says, “and that’s what contributes to the problem, because eventually you’re oblivious to a lot that’s around you.” Research has demonstrated cell phone use reduces a driver’s field of vision, creating a cone-like field of view akin to tunnel vision. Other studies have suggested using a cell phone while driving places a mental burden, or “cognitive load,” on drivers, making them less likely to detect and react to the appearance of a new object.Vecera and his team wanted to explore why the brain was burdened with something as simple as having a conversation. After all, why would talking on the phone affect your ability to pay attention to the road?Engaging in conversation, whether on the phone or with someone in the vehicle, “seems effortless,” Vecera noted. But it’s far more complex than one would think. The brain is absorbing information, overlaying what you know (and what you don’t), and then preparing to construct a thoughtful reply. “That’s all very effortful,” Vecera continued. “We do it extremely rapidly, so rapidly we don’t grasp how difficult it really is.” The study is published online in the journal Psychonomic Bulletin and Review.